Today's Message Index:
----------------------
1. 05:51 AM - Re: Z14 contactor(s) circuit question (Ken)
2. 07:55 AM - Re: Avionics Switch (Roger Bentlage)
3. 09:57 AM - "Broken and Garbled" (Ron Patterson)
4. 12:10 PM - Re: Z14 contactor(s) circuit question (Robert L. Nuckolls, III)
5. 03:34 PM - Re: Homemade Avionics/Electrical component bench tester (Robert L. Nuckolls, III)
6. 04:21 PM - Re: Homemade Avionics/Electrical component bench tester (Ernest Christley)
7. 06:44 PM - Re: Back-Up Battery ground (Speedy11@aol.com)
Message 1
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| Subject: | Re: Z14 contactor(s) circuit question |
Hi Rick
FWIW I believe I added a fuse link (about two inches of 26awg wire
inside glass sphaghetti as per the B&C kit) anywhere that I reduced
wiring size to 22awg from a heavier than 5 amp protected circuit. As you
say, the risk of the specific failure that you describe has to be very
low so I think a fuse link makes more sense than a fuse. They don't
really take up space and I would expect no corrosion or maintanance
issues within a couple of lifetimes...
Ken
rtitsworth wrote:
>
>Bob, etal,
>
>I noticed on the Z-14 schematic there is not a breaker, nor fuse, nor
>fuseable link, anywhere along the current path from the battery(s) to the
>battery contactor master switch(es) on the panel (and then to ground).
>
>A short (wire failed to ground) between the contactor and the switch would
>just keep the contactor closed (the same as the switch being on) and thus no
>risk of additional damage, fire, etc. (due to the resistance of the
>contactor coil).
>
>However, if the contactor itself failed internally and shorted the power
>terminal to the switch/coil terminal, it seems the 22AWG switch wire would
>fry.
>
>Perhaps the likelihood of that is so remote as to outweigh the complexity/
>risk of an additional component in the circuit. However, breakers and fuses
>are pretty reliable and with Z14 there is Bus#2 and the cross tie, which
>could be used if the #1 master breaker/fuse failed and caused the #1
>contactor to open (and/or vise versa).
>
>Thus, I am thinking of perhaps putting a fuse(s) in-line with the master
>switch(es). Thoughts?
>
>Rick
>
>
Message 2
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| Subject: | Re: Avionics Switch |
Steve,
I have completed the electrical/avionics portion of a RV-7. It's a dual batt,
dual alt, dual electronic ignition, all glass panel, etc. I opted for avionics
master (2) switches although there seem to be arguments against their necessity.
I will attempt to attach a .DXF file of the electrical schematic and pic of the
panel.
If that doesn't work I'll be glad to send them seperately if you're interested.
Roger
RV-7 finishing (at last)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=83764#83764
Attachments:
http://forums.matronics.com//files/instrument_panel_2_1_186.jpg
Message 3
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| Subject: | "Broken and Garbled" |
I have had poor reception from towered airports with my XCOM and now that my radio
is out for repair, poorly received transmissions with my ICOM handheld A5.
I've even tried hooking up my aircraft Comant antenna to the ICOM but it didn't
improve how others hear me (or don't). Could I need some filter or something?
This seriously limits my entry into controlled airspace so any fix ideas are
appreciated.
Ron - RV-4
N8ZD@yahoo.com
Message 4
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| Subject: | Re: Z14 contactor(s) circuit question |
At 10:06 PM 12/26/2006 -0500, you wrote:
><rtitsworth@mindspring.com>
>
>Bob, etal,
>
>I noticed on the Z-14 schematic there is not a breaker, nor fuse, nor
>fuseable link, anywhere along the current path from the battery(s) to the
>battery contactor master switch(es) on the panel (and then to ground).
>
>A short (wire failed to ground) between the contactor and the switch would
>just keep the contactor closed (the same as the switch being on) and thus no
>risk of additional damage, fire, etc. (due to the resistance of the
>contactor coil).
>
>However, if the contactor itself failed internally and shorted the power
>terminal to the switch/coil terminal, it seems the 22AWG switch wire would
>fry.
>
>Perhaps the likelihood of that is so remote as to outweigh the complexity/
>risk of an additional component in the circuit. However, breakers and fuses
>are pretty reliable and with Z14 there is Bus#2 and the cross tie, which
>could be used if the #1 master breaker/fuse failed and caused the #1
>contactor to open (and/or vise versa).
>
>Thus, I am thinking of perhaps putting a fuse(s) in-line with the master
>switch(es). Thoughts?
Your hypothesized failure is somewhere on the same
order of probability as being hit by a meteor while
on short final. The published configurations have been
evaluated MANY times for nearly a century but have
remained unchanged. I can see no return on investment
for adding this feature.
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
Message 5
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| Subject: | Re: Homemade Avionics/Electrical component bench |
tester
At 09:19 PM 12/26/2006 -0800, you wrote:
>
>Anybody have a lead on plans/instructions for a simple homemade avionics
>bench tester? One that would include a 12V battery, batter charger, and a
>box with a couple of switches and 3-4 different amp circuits protected by
>fuses? The idea would be to drive the various electonic components simply
>by hooking them into the correct circuit, based on its current draw;
>thinks like lights, flashers, servos, etc..
Your words don't paint a lucid image of
your request. "Bench testing" is generally
the simplest combination of power supply,
input-output simulation and interconnections
to allow a technician to exercise and/or troubleshoot
any given device's capabilities. This isn't so
much a "tester" as a combination of tools
chosen and assembled for a specific task.
At the other extreme, one might consider
bench top simulators where ALL the components
of a proposed system may be operated together
and exercised to explore and prove functionality
of each system's features and inter-system
integration issues.
I'd suggest you begin by acquiring the rudimentary
test tools. Multimeter and power supply. There
are some excellent buys on the 'net. We have
perhaps a dozen power supplies in our shop of all
sizes but one of my favorites is similar to this
one:
http://tinyurl.com/ycj6wu
Many accessories can be powered up with just
a bench supply. This particular supply will allow you
to adjust voltage and measure the appliance's current
draw.
Each appliance calls for its own "test fixture" . . .
the connectors, wires, controls and input/output ports
needed to exercise that particular appliance. Here . . .
http://www.aeroelectric.com/Pictures/Tools/Test_Fixtures.jpg
is but a handful of hundreds of fixtures that I've crafted
over the years to exercise various pieces of airplane hardware
on the bench. This is why your request for A schematic
for A test fixture didn't ring any bells as to a simple
answer. Perhaps I mis-understood your question and you
can elaborate further?
Bob . . .
Message 6
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| Subject: | Re: Homemade Avionics/Electrical component bench |
tester
Robert L. Nuckolls, III wrote:
>
> I'd suggest you begin by acquiring the rudimentary
> test tools. Multimeter and power supply.
This is for the true, die-hard, born'n'bread cheapskates, like myself.
Harbor Freight has multimeters for $3 nearly all the time. That's cheap
enough that I don't have to waste time wondering where I put my meter.
I just sprinkle the shop with a liberal supply.
A 12V power supply can be had for nothing by grabbing the next ATX
computer you see someone throwing out. Scavenge the power supply. It
will give you a steady 12V if you connect the GREEN wire to one of the
BLACK wires. It won't turn on otherwise. It also has a range of other
voltages, usually printed on the side of the power supply. I have one
installed placed where my battery will go, allowing me to test things as
they're installed. It's only good for a few amps, but the price is right.
Message 7
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| Subject: | Re: Back-Up Battery ground |
Carlos,
Good luck getting a helpful answer on this list. You can normally get little
more than criticism and ridicule.
It sounds as though you have a ground wire running from your main battery to
the aft portion of the fuselage and you want to know if connecting your
back-up battery in the aft fuselage to that same ground wire will cause any
problems. Is that correct?
Stan Sutterfield
Do not archive
Please forget the reason why I may want to put the Avionics Back-Up battery
in the tail, and please answer the electric questions:
- Can I connect the (-) terminal of that battery to the tail's ground lug,
which is isolated from the fuselage and is directly connected to the (-)
terminal of the "Main" battery ?
- Can I continue to use that same ground lug to connect the other grounds
( from the tail light, the strobe beacon, and the elevator trim motor)
there?
- Isn't there any possibility of "ground loop"?
Carlos
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